Base for a rail insulator



FIG. 1 is a perspective view of a base for a rail insulator showing a first embodiment of my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is a perspective view of a base for a rail insulator showing a second embodiment of my new design;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a side elevational view thereof;

FIG. 9 is a perspective view of a base for a rail insulator showing a third embodiment of my new design;

FIG. 10 is a top plan view thereof;

FIG. 11 is a bottom plan view thereof; and,

FIG. 12 is a side elevational view thereof.

The parts shown in broken lines in FIGS. 1-12 form no part of the claimed design. 

CLAIM The ornamental design for a base for a rail insulator, as shown and described. 